Compiler warnings on macOS

[FonsRademakers]

• Checked for duplicates

Describe the bug

Number of compiler warnings on unused variables on macOS:

/Users/rdm/rootsrc/core/unix/src/TUnixSystem.cxx:4967:17: warning: variable 'vsize' set but not used [-Wunused-but-set-variable]
      vm_size_t vsize, vprvt, rsize, size;
                ^
1 warning generated.
[6852/9530] Linking CXX static library lib/libclingUtils.a
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib: file: lib/libclingUtils.a(PlatformWin.cpp.o) has no symbols
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib: file: lib/libclingUtils.a(PlatformWin.cpp.o) has no symbols
[8118/9530] Building CXX object proof/proof/CMakeFiles/Proof.dir/src/TProof.cxx.o
/Users/rdm/rootsrc/proof/proof/src/TProof.cxx:1047:11: warning: variable 'cpuPin' set but not used [-Wunused-but-set-variable]
   Bool_t cpuPin = kFALSE;
          ^
1 warning generated.
[8195/9530] Building CXX object graf2d/asimage/CMakeFiles/ASImage.dir/src/TASImage.cxx.o
/Users/rdm/rootsrc/graf2d/asimage/src/TASImage.cxx:2200:13: warning: variable 'disp' set but not used [-Wunused-but-set-variable]
   Display *disp;
            ^
1 warning generated.
[8199/9530] Building CXX object graf2d/gpad/CMakeFiles/Gpad.dir/src/TPad.cxx.o
/Users/rdm/rootsrc/graf2d/gpad/src/TPad.cxx:1535:34: warning: variable 'pxold' set but not used [-Wunused-but-set-variable]
   Int_t pxmin,pxmax,pymin,pymax,pxold,pyold,px,py;
                                 ^
/Users/rdm/rootsrc/graf2d/gpad/src/TPad.cxx:1535:40: warning: variable 'pyold' set but not used [-Wunused-but-set-variable]
   Int_t pxmin,pxmax,pymin,pymax,pxold,pyold,px,py;
                                       ^
2 warnings generated.
[8316/9530] Building CXX object gui/gui/CMakeFiles/Gui.dir/src/TGView.cxx.o
/Users/rdm/rootsrc/gui/gui/src/TGView.cxx:467:36: warning: variable 'cpyheight' set but not used [-Wunused-but-set-variable]
   Int_t xsrc, ysrc, xdest, ydest, cpyheight, cpywidth;
                                   ^
/Users/rdm/rootsrc/gui/gui/src/TGView.cxx:467:47: warning: variable 'cpywidth' set but not used [-Wunused-but-set-variable]
   Int_t xsrc, ysrc, xdest, ydest, cpyheight, cpywidth;
                                              ^
2 warnings generated.
[8479/9530] Building CXX object graf2d/cocoa/CMakeFiles/GCocoa.dir/src/MenuLoader.mm.o
/Users/rdm/rootsrc/graf2d/cocoa/src/MenuLoader.mm:92:16: warning: variable 'menuItem' set but not used [-Wunused-but-set-variable]
   NSMenuItem *menuItem = [aMenu addItemWithTitle : NSLocalizedString(@"Minimize", nil)
               ^
1 warning generated.
[8627/9530] Building CXX object gui/fitpanel/CMakeFiles/FitPanel.dir/src/TFitEditor.cxx.o
/Users/rdm/rootsrc/gui/fitpanel/src/TFitEditor.cxx:2806:26: warning: variable 'py1old' set but not used [-Wunused-but-set-variable]
   static Int_t  px1old, py1old, px2old, py2old; // to remember the square drawn.
                         ^
/Users/rdm/rootsrc/gui/fitpanel/src/TFitEditor.cxx:2806:34: warning: variable 'px2old' set but not used [-Wunused-but-set-variable]
   static Int_t  px1old, py1old, px2old, py2old; // to remember the square drawn.
                                 ^
/Users/rdm/rootsrc/gui/fitpanel/src/TFitEditor.cxx:2806:42: warning: variable 'py2old' set but not used [-Wunused-but-set-variable]
   static Int_t  px1old, py1old, px2old, py2old; // to remember the square drawn.
                                         ^
/Users/rdm/rootsrc/gui/fitpanel/src/TFitEditor.cxx:2806:18: warning: variable 'px1old' set but not used [-Wunused-but-set-variable]
   static Int_t  px1old, py1old, px2old, py2old; // to remember the square drawn.
                 ^
4 warnings generated.

Expected behavior

No warnings.

To Reproduce

Compile on macOS with Cocoa.

Setup

Current master.

Additional context